The specific aim of this application is to gain a state-of-the-art high resolution Scanning Electron Microscope to serve the research needs of the School of Dentistry and the Dental Research Institute (DRI) of The University of Michigan. Twenty-one departments of the School of Dentistry were surveyed and the majority have staff in need of high quality SEM. Each of these departments have graduate students who also need SEM. Several of these projects are described in detail and represent research in the Departments of Materials, Engineering and Pathology. The Dental Research Institute has three major program areas: Dental Caries, Periodontal Disease and Antiviral Chemotherapy. These areas include DRI and School scientists involved in dental engineering, microbiology, cell biology, chemistry, histology, pharmacology, pathology and molecular biology that need electron microscopy to enhance their research. The DRI is one of five funded by NIH in the United States. To assist the scientists in the Institute and the Dental School, an electron microscope facility was developed six years ago. This unit currently maintains three transmission EM scopes as well as ultramicrotomes, a vacuum evaporator, lyophilization equipment and dark room facilities. A full-time manager is employed and is assisted by several photographers and technicians. The proposed SEM would thus be capably handled by a professonal who would maintain and schedule its use. The Institute has stable funding and thus offers long-term management of the proposed instrument. In the past year Institute scientists published 52 papers and have 26 in press as well as presented 66 papers at national and international meetings. SEM is needed in several projects in each program area. Dental Caries: investigators on evaluating the surface enamel to determine characteristics of pores that cause sub-surface demineralization. Another group of physical chemists have evolved in a calcium fluoride gel to remineralize these lesions and evaluations of success is needed. Periodontal Disease: studies of basal lamina and collagen growth utilize both TEM and SEM. Antiviral Chemotherapy have utilized TEM on viral study and SEM on evaluation of herpetic lesion with and without antiviral compounds.